• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.236-237
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• 2000

LCD(liquid crystal display)에서 칼라를 만드는 방법에는 가색 혼법(additive color method)$^{(1)}$ 과 감색 혼법(subtractive color method)$^{(2).(3)}$ 이 있다. 가색 혼법은 빛의 3원색인 red, green, blue의 칼라 필터를 인접하게 배치시키고 각각의 칼라 필터에 해당 칼라의 신호를 인가하여 밝기를 제어함으로서 색을 표현하는 방법으로 대비비(contrast ratio)가 높고 표현할 수 있는 색상의 범위(gamut)가 넓고 액정 셀의 두께가 얇다는 장점이 있지만, 반면에 빛의 투과율이 낮다는 단점이 있다. 거기에 비해 감색 혼법은 cyan, magenta, yellow의 3색의 표시소자로서 3-stack을 구성하여, 각층에 해당 칼라의 신호를 인가하여 밝기를 제어함으로서 색을 표현하는 방식으로 광 투과량은 가색 혼법의 경우보다 높으나, 완전한 dark상태의 구현이 어렵기 때문에 명암대비비가 낮다는 단점이 있다. (중략)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.130-131
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• 2007

지방족 액정 계면활성제를 주형물질로 이용, 화학석출을 통해 나노채널을 갖는 금속미립자를 제조하였다. 편광현미경을 이용한 상태도 분석을 통해 헥사고날 구조를 갖는 주형생성 조건을 결정하였으며, 주형의 배열을 방해하지 않고 화학석출이 가능하도록 환원제의 종류, 농도 및 석출방식 등을 조절하였다. 제조된 금속미립자는 입도분석기를 이용하여 평균입경을 측정하였고, TEM 분석을 통해 나노채널의 형성여부를 확인하였다. BET를 이용한 표면적 측정결과, 비표면적이 $112.6m^2/g$로 나노채널 형성으로 인해 비표면적이 크게 증가하였음을 알 수 있었다.

• Polymer(Korea)
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• v.28 no.4
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• pp.314-320
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• 2004

Soluble aromatic polyimides bearing 4-(4-oxyalkyleneoxystyryl)- pyridines (ethylene and hexylene) as photoreactive side groups were synthesized and characterized. The photoreactive polymers were soluble in various polar organic solvents and their films were easily formed by solution casting. The photoreactivities of the polymers in the film state were approximately 64% at an exposure energy of 1.5 J/$\textrm{cm}^2$. Transmittances of the polymer films were about 85% after annealing at 20$0^{\circ}C$. Therefore, these polymers can be evaluated to be photoreactive polyimides with good transparency and solubility. The dichroic ratios of the polymers with ethylene and hexylene groups as the alkylene spacers were 0.023 and 0.026, respectively. The order parameters of 4'-pentyl-4-bipheny1carbonitrile as a liquid crystal (LC) in the film cells of the former and latter polymers were 0.50 and 0.52, respectively. These results indicate that the polymers show the effect of alkylene spacer on the photoalignments. The LC in the film cells of the polymers was perpendicularly oriented to the electric vector of the linear polarized UV light (LPUVL).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.503-516
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• 2001

At present, environmental control system of greenhouses related with industrial automation in the korea is composed of on/off-type control machine using a timer in facilities requiring intensive labor. This system, however, makes it difficult for us to find out any status of environmental control system in greenhouses when we are situated in a remote area or at midnight. In this paper we improved a system to monitor status for manual and automatic control by means of PC by replacing an existing on/off-type controller with a display panel, It also attempts to implement DB for information on corps and to provide a user with the efficiency of getting information for plants.

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.386-390
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• 1999

Erasable polarization holographic grating was recorded with two-wave mixing in PCN which was side-chain liquid crystalline polymalonic esters containing two symmetrical 4-cyanoazobenzene as photoresponsive groups. The diffraction efficiency of recorded grating was measured and the characteristics of recording, decay in a dark room and erasing by circularly polarized light were investigated. As the results, birefringence, $\Delta$n of PCN was measured $6.5{\times}10^{-2}$, which was 0~100 times higher than those of crystals such as Fe:$LiNbO_3$, Ce:$BaTiO_3$ crystals. Dark decay rates was $4.3{\times}10^{-5}$ %/hour, which showed the possibility of application as data storage media.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.3
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• pp.373-385
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• 1998

The local Nusselt numbers have been measured for a round turbulent jet impinging on the convex surface with and without rib. Liquid crystal/transient method was used to determine the Nusselt number distributions along the surface. The temperature on the surface was measured to within .+-.0.25 deg. C accuracy using liquid crystal and a digital color image processing system. The experiments were made for the jet Reynolds number (Re) 23,000, the dimensionless nozzle-to-surface distance (L/d) from 6 to 10, the dimensionless surface curvature (d/D) 0.056, and the various rib types (height(d$_{1}$) from 1 to 2 mm, pitch (p) from 6 to 32 mm). It was found that the average Nusselt numbers on the convex surface with rib are higher than those without rib, mainly due to an increase in the turbulent intensity caused by flow separation, recirculation and reattachment on the wall surface. In addition, we compared the results by the steady-state method using the gold-film Intrex with those by the transient method.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.4
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• pp.569-574
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• 2013

With probably too many smart phone applications downloaded, it is sometimes frustrating to find frequently used applications quickly. In this paper, we propose a learning application that learns what applications a user frequently uses and match them with several signals that user designated. This learning applications uses ART2 algorithm that is good for stable real-time learning. By executing this learning application, a user simply chooses an application that is to be quickly searched and then draw a figure that would match the designated application at the upper left corner of our learning application. The proposed learning application transforms the background with 0's and the figure with 1's and normalize them to be used as inputs for ART2 and ART2 does clustering to setup a match table between applications and figures. After learning, a user simply draws a figure to execute one's frequently used application.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.485-488
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• 2007

$SF_6$(sulfur hexafluoride)는 뛰어난 단열 및 아크방지능력(arc-extinguishingproperty)으로 인해, 전력용 변압기의 절연가스와 반도체${\cdot}$액정용 플라즈마 CVD로의 cleaning gas, 주물공장 covering gas 등으로 사용되고 있다. 하지만, $SF_6$의 지구온난화지수(global warming potential)는 $CO_2$대비 23,900배가 높아 기후변화에 미치는 영향이 $CO_2$보다 훨씬 크고, 대기 중 분해되지 않고 잔존하는 기간이 $CH_4$ 10년, $CO_2$ 및 CFCs는 100년으로 추정되는데 반해, $SF_6$는 3,200년으로 연간방출양이 작더라도 오랜 기간 누적되면 그 파장이 클 것으로 사료된다. 대부분의 가스 하이드레이트(고상결정상태)는 고압, 저온에서 형성가능 하지만, 불화가스에 대해서는 쉽게 결정화가 일어난다. $SF_6$는 3$^{\circ}C$, 2기압에서 고밀도 고상화가 되기 때문에 여러 기체와 흔합되어 있는 경우 $SF_6$만을 압축된 고상 결정상태를 형성, $SF_6$를 회수, 정제할 수 있으므로 불화가스 분리${\cdot}$회수에 기술적, 경제적 효과를 기대할 수 있다. 본 연구에서는 하이드레이트 촉진제로서 계면활성제(promoter) 첨가에 따른 $SF_6$ 하이드레이트 형성 및 해리과정 실험을 통해 효율적인 $SF_6$ 저감에 관한 적용기술을 연구해 보았다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.107-107
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• 2010

ZnO는 상온에서 에너지 밴드갭이 3.37 eV 이고 엑시톤 속박에너지가 60 meV 인 넓은 에너지 띠를 가진 반도체이다. ZnO 반도체는 고에너지 영역에서 광투과율 및 에너지 수집율이 큰 특성을 가지고 있기 때문에 단파장 영역에서 작동하는 발광 다이오드나 반도체레이저 소자 응용에 사용되고 있다. 이와 더불어 액정디스플레이, 유기발광소자 및 태양전지에서 투명 산화물 전극으로 많은 응용이 되고 있다. 본 연구에서는 p-type Si 기판 위에 ZnO 나노입자 형성과 구조적 성질과 전자적 성질에 대하여 조사하였다. ZnO 나노입자를 형성하기 위해 ethanol에 zinc acetate dehydrate (5 wt%)을 적절히 분산시킨 $Zn(CH_3COO)_2H_2O\;+\;CH_3OH$ 용액을 스핀 코팅하여 산소 분위기에서 각각 $300^{\circ}C$, $500^{\circ}C$, $700^{\circ}C$ 및 $900^{\circ}C$로 각각 2시간 동안 열처리 하였다. X-ray 회절 실험 결과는 열처리 온도에 관계없이 ZnO (0001)의 피크가 관측되었다. 원자힘 현미경 이미지상으로 열처리 온도에 따른 ZnO 나노입자의 표면상태의 변화와 나노입자의 크기의 변화를 확인하였다. X-ray 광전자 분광 스펙트럼 결과는 Zn $2p_{3/2}$와 O 1s의 전자상태 스펙트럼을 분석하여 ZnO 나노입자가 형성됨을 보여주었다. 본 연구를 통하여 용액방법을 사용하여 제작된 ZnO 나노입자의 열처리 온도변화에 따른 구조적 성질과 전자적 성질을 이해하는데 도움을 줄 것이다.

• Korean Journal of Crystallography
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• v.2 no.2
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• pp.13-21
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• 1991

X-ray methods have been used to determine the chain conformation and packing of the thermotropic liquid crystalline copolyester prepared from 50% tarephthaloyl chloride(TPA) and 50% (1-phenylethyl) hydroquinone(PEHQ). The x-ray patterns of annealed melt-spun fibers contain a series of annealed melt-Pointing to a well ordered crystalline structure, despite the random sense(2 or 3-) of the 1-phenylethyl substiuttion on the TPA-hydroquinone backbone. The crystalline fiber is monoclinic with space group P2l and the unit cell has dimensions 11=12.77 A, b=10.17 A (upique axis), c=12.58 h (fiber axis). and β=90.1° and contains TPA-PEHO units of to or chains. The random substitution of 1-phenylethyl groups was modelled by placing these groups at both the 2and 3 positions and giving each a weight of one-hal(. T he structure has been refined by linked a rom least square methods(LALS) against 16 observed and 21 unobserved reflections. and had a final R value of 0.20. Packing of the side chains is effected by staggering adjacent chains along the b axis by approximately c/2, so that the side chains are interleaved. The phenyl-COO and COO-phenyl torsion angles are -6.1 and 65.6, respectively, such that the main chain phenyls are mutually inclined at 59.5 (the ester groups are assumed to be planar). These torsion angles compare very well with those for the model compounds, notably phenylbenzoate, and can be used in future analyses of the structures of more complex random sequence copolyesters.